The WebContent process does not suspend when MiniBrowser is minimized.
https://bugs.webkit.org/show_bug.cgi?id=187708

Reviewed by Chris Dumez.

Source/WebCore/PAL:

Add function for enabling App nap.

* pal/spi/cf/CFUtilitiesSPI.h:

Source/WebKit:

Using the NSRunLoop runloop type prevents the WebContent process from suspending. Instead, use the new
_WebKit runloop type. Also do not leak a boost to the WebContent process, since this also prevents the
WebContent process from going to sleep. Calling SetApplicationIsDaemon prevents the WebContent process
from being assigned the application process priority level. To block WindowServer connections, call
CGSSetDenyWindowServerConnections(true) instead. Finally, App nap must be manually enabled, since the
WebContent process is no longer a NSApplication.